Molecular sieves are a commercially important class of crystalline materials. They have distinct crystal structures with ordered pore structures which are demonstrated by distinct X-ray diffraction patterns. The crystal structure defines cavities and pores which are characteristic of the different species.
Molecular sieves having the MTT framework topology defined by the connectivity of the tetrahedral atoms (referred to herein simply as MTT or MTT molecular sieve) are known. See, for example, Ch. Baerlocher et al., Atlas of Zeolite Framework Types, 5th Revised Edition, 2001 of the International Zeolite Association. Examples of MTT molecular sieves include the zeolite designated “SSZ-32”, SSZ-32 and methods for making it are disclosed in U.S. Pat. No. 5,053,373, issued Oct. 1, 1991 to Zones. This patent discloses the preparation of zeolite SSZ-32 using an N-lower alkyl-N′-isopropylimidazolium cation as an organic structure directing agent (SDA), sometimes called a templating agent. U.S. Pat. No. 4,076,842, issued Feb. 28, 1978 to Plank et al., discloses the preparation of the zeolite designated “ZSM-23”, a zeolite with a structure similar to SSZ-32, using a cation derived from pyrrolidine as the SDA. Zeolites SSZ-32 and ZSM-23 are commonly referred to as having the MTT framework topology. Both of the aforementioned patents are incorporated herein by reference in their entirety. Other MTT zeolites include EU-13, ISI-4 and KZ-1.
U.S. Patent Application Publication No. 2005/0092651, published May 5, 2005 by Zones et al., discloses a small crystal SSZ-32 zeolite, designated SSZ-32X, having a mole ratio of silicon oxide to aluminum oxide greater than about 20:1 to less than 40:1 with crystallites having broad lathe-like components in the range of 200-400 Angstroms. U.S. Patent Application Publication No. 2005/0092651 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,558,851, issued Sep. 24, 1996 to Miller, discloses a method for preparing a crystalline aluminosilicate zeolite from a reaction mixture containing only sufficient water so that the reaction mixture may be shaped if desired. In the method, the reaction mixture is heated at crystallization conditions and in the absence of an external liquid phase, so that excess liquid need not be removed from the crystallized material prior to drying the crystals. U.S. Pat. No. 5,558,851 is incorporated by reference herein in its entirety.